1. Field of the Invention
This document relates to a touch sensing system and a driving method thereof.
2. Discussion of the Related Art
User interface (UI) is configured so that users are able to communicate with various electronic devices and thus can easily and comfortably control the electronic devices as they desire. Examples of the user interface include a keypad, a keyboard, a mouse, an on-screen display (OSD), and a remote controller having an infrared communication function or a radio frequency (RF) communication function. User interface technologies have continuously evolved to increase user's sensibility and handling convenience. The user interface has been recently developed to include touch UI, voice recognition UI, 3D UI, etc.
The touch UI has been necessarily used in portable information appliances. The touch UI has been implemented by a method for forming a touch screen on the screen of a display device. A capacitive touch screen detects touch input by sensing a change in capacitance, i.e., a change in the amount of electric charge in a touch sensor, when a finger or conductive material touches a touch sensor.
In order to increase the touch sensitivity of the touch UI, it is necessary to increase touch report rate. The touch report rate is a velocity (Hz) at which coordinate data obtained by sensing all touch sensors present within a touch screen TSP. The higher the touch report rate, the less the time gap between the actual timing of touch input and the input response time and the higher the touch sensitivity that a user feels.
As shown in FIG. 1, a related art touch sensing system applies a drive signal to all touch sensors within a touch screen during a sensing period, senses a change in the amount of electric charge in the touch sensors, generates N frames (N is a positive integer) of raw data, transmits the N frames of raw data to an external algorithm execution unit during a raw data transmission period, and then analyzes the N frames of raw data to calculate the coordinates of a touch input position during an algorithm execution period. Next, the related art touch sensing system applies a drive signal to all the touch sensors within the touch screen during a sensing period, senses a change in the amount of electric charge in the touch sensors, generates (N+1) frames of raw data, transmits the (N+1) frames of raw data to the external algorithm execution unit during a raw data transmission period, and then analyzes the (N+1) frames of raw data to calculate the coordinates of a touch input position during an algorithm execution period. An algorithm for coordinate calculation is executed after waiting an amount of time equal to the sum of the sensing period of all the touch sensors and a raw data transmission period. Accordingly, it is difficult to improve touch rate report and reduce latency in the related art. Latency refers to the time it takes from the touch sensing start time until the transmission of coordinate information of touch input to a host system.